Running for office costs money: staff, advertising, travel, and getting out the vote. How that money may be raised and spent has been shaped as much by court decisions as by Congress.

In 2010, in Citizens United v. Federal Election Commission, the Supreme Court ruled 5–4 that the government may not ban independent political spending by corporations and unions. Later that year a federal appeals court decision, SpeechNow.org v. FEC, led to “super PACs”: committees that may raise unlimited amounts as long as they do not coordinate with a candidate.

Contributions directly to candidates are still limited, and campaigns, parties and PACs report their donors to the Federal Election Commission. Some groups that spend on politics, such as certain nonprofits, are not required to name their donors, which is why that spending is sometimes called “dark money.”

Two views

Supporters of the current rules see political spending as protected speech and say more spending means more information for voters. Critics say large donors gain outsized influence and that undisclosed spending keeps voters from knowing who is behind an ad.

Every federal candidate’s fundraising is public. The FEC’s website lets anyone look up who gave to a campaign, how much, and how the campaign spent it.

Before you vote, look up the candidates’ reports at fec.gov, or your state’s campaign finance site for state races, and see where their money comes from.